Evaluation of the dose response and exposure to saccharin in the rat

A two-generation bioassay on sodium saccharin (NaS), involving 2500 second-generation male rats, was designed to determine the dose response for urinary bladder tumours in male rats and to evaluate other changes possibly related to the occurrence of the tumours. Changes in urine volume and urine osmolality were highly correlated with the occurrence of the urinary bladder tumours. The bladder tumour incidence in rats exposed to NaS only during gestation was comparable to that of the untreated controls, and that in rats exposed to NaS from birth for two generations, but the need to lower the dietary level from 5.0 to 3.0% during the study reduced the value of this group for comparing the physiological effects and tumour incidence following NaH treatment with those in NaS-treated rats.